Savings Calculator
This savings calculator estimates how a savings balance may grow over time based on your starting amount, monthly contribution, annual interest rate, time horizon, and compounding frequency. Enter what you already have saved, how much you plan to add each month, and the interest rate your account pays, and the tool projects an ending balance along with total contributions and total interest earned. It works for a regular savings account, a high-yield savings account, a money market account, or any goal where you are setting aside a fixed amount on a schedule and letting interest compound in the background. The projection is a planning estimate, not a guarantee, since real bank rates change and most people adjust their contributions as income and priorities shift.
Quick answer
Ending balance depends on four inputs working together: starting balance, monthly contribution, annual interest rate, and time horizon in years.
What this tells you
- •Ending balance depends on four inputs working together: starting balance, monthly contribution, annual interest rate, and time horizon in years.
- •Compounding frequency (monthly, quarterly, or annually) controls how often interest gets added to the balance and starts earning its own interest.
- •Your monthly contribution is converted to match the compounding schedule you pick, so a monthly amount still applies correctly under quarterly or annual compounding.
- •Consistent contributions matter more than the interest rate for most short and medium-term goals, since deposits build the base balance that interest is calculated on.
- •Total interest earned is the difference between the ending balance and the sum of your starting balance plus all contributions.
- •Outputs are projections based on fixed assumptions, not guaranteed account performance.
How to Use
- 1Enter your starting savings balance. Use 0 if you are starting a new account or new goal from scratch.
- 2Enter your planned monthly contribution, the amount you intend to deposit every month regardless of the compounding frequency you choose.
- 3Enter the annual interest rate your account pays as a percentage, such as 4.5 for 4.5%, not 0.045.
- 4Enter the number of years you plan to save, using decimals for partial years such as 2.5 for two and a half years.
- 5Choose a compounding frequency (monthly, quarterly, or annually) and calculate to see your estimated ending balance, total contributions, total saved, and total interest earned.
How It Works
Formula
Each period: balance(next) = balance(current) + interest + contribution
interest = balance(current) x periodic rate
periodic rate = annual rate / 100 / compounds per year
contribution per period = (monthly contribution x 12) / compounds per yearThe calculator steps forward one compounding period at a time. In every period it calculates interest as the current balance multiplied by the periodic rate, adds that interest to a running interest total, then adds both the interest and the contribution for that period to the balance. The periodic rate is your annual rate divided by 100 and divided by the compounding frequency, so a 4.5% annual rate with monthly compounding uses a 0.375% monthly rate. Your monthly contribution is annualized (multiplied by 12) and then divided by the compounding frequency, which is how a monthly dollar amount still lines up correctly if you pick quarterly or annual compounding instead of monthly. Total periods equal years multiplied by compounding frequency, rounded to the nearest whole period. This model assumes the interest rate and contribution amount stay fixed for the entire time horizon.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Steady monthly saver
Over 120 monthly periods at a 0.375% monthly rate, total contributions reach $36,000 on top of the $5,000 starting balance, for $41,000 total saved. The remaining $12,194.39 of the ending balance comes from compounded interest, which is more than 30% of everything contributed.
Starting an emergency fund from zero
With no starting balance, the full $12,000 in contributions over 5 years builds the base, and interest adds $929.34 on top. This is a realistic timeline for building a 3 to 6 month emergency fund from scratch in a standard savings account.
Long-term goal with annual compounding
Across 20 annual periods, total contributions of $120,000 plus the $10,000 starting balance add up to $130,000 saved, while compounding adds $94,928.70 in interest. Annual compounding credits interest less often than monthly compounding, so the same rate and contributions produce a smaller ending balance than an equivalent monthly-compounding scenario would.
Short-term goal with quarterly compounding
Over 12 quarterly periods, $3,600 in contributions plus the $1,000 starting balance reach $4,600 total saved, and interest contributes $162.35. Short time horizons and modest rates mean interest plays a small role compared to the deposits themselves.
High-yield savings account boost
A higher 4.8% rate on a shorter 2-year horizon still adds a meaningful $371.66 in interest on top of $3,600 in contributions and the $2,000 starting balance. This scenario reflects how a high-yield savings account can noticeably outperform a standard low-rate account even over a short period.
Lump sum with no ongoing contributions
With no monthly contributions, the entire $4,837.71 in growth comes from compounding alone on the original $15,000. This isolates what pure compound interest does to a lump sum when nothing else is added, which is useful for comparing a deposit-only account to one you plan to keep funding.
Six-month emergency fund on a $2,800 budget
Keisha spends about $2,800 a month and wants six months of expenses, $16,800, parked in a high-yield savings account. She starts with $1,800 and moves $350 across on each payday. After 42 monthly periods the balance is $17,820.64: $14,700 of deposits, the $1,800 she began with, and $1,320.64 of interest. Her own money alone reaches only $16,500, so interest is what carries the fund past the goal, and she crosses $16,800 in month 40 if the rate holds. The whole balance sits well inside the FDIC limit, and the interest is taxable in the year it posts.
Balance After $200 a Month at Common Savings Rates
Ending balance for a $200 monthly deposit from a $0 start with monthly compounding, computed with this calculator. Compare any balance with the deposit totals in the note to see how much interest contributes at each rate and horizon.
| Years | 2% | 3% | 4% | 5% |
|---|---|---|---|---|
| 1 | $2,422.12 | $2,433.28 | $2,444.49 | $2,455.77 |
| 2 | $4,893.13 | $4,940.56 | $4,988.58 | $5,037.18 |
| 3 | $7,414.02 | $7,524.11 | $7,636.31 | $7,750.67 |
| 5 | $12,609.47 | $12,929.34 | $13,259.80 | $13,601.22 |
| 7 | $18,016.77 | $18,668.38 | $19,350.83 | $20,065.73 |
| 10 | $26,543.93 | $27,948.28 | $29,449.96 | $31,056.46 |
| 15 | $41,942.61 | $45,394.54 | $49,218.10 | $53,457.79 |
| 20 | $58,959.37 | $65,660.40 | $73,354.93 | $82,206.73 |
Computed with the formula above: $0 start, $200 added at the end of each month, the rate divided by 12 and compounded monthly, rounded to cents. Deposits alone total $2,400 after 1 year, $12,000 after 5, $24,000 after 10, and $48,000 after 20, so the rest of each balance is interest. Banks must quote an annual percentage yield on every deposit account under Regulation DD (12 CFR 1030.4(b)), and an APY already includes compounding, so a quoted APY entered as the rate here overstates the balance slightly (4% entered compounds to 4.07%).
APY, Deposit Timing, Insurance, and Taxes
The interest rate is the simple annual rate a bank pays, and the annual percentage yield (APY) is what that rate earns over a year once compounding is included. Regulation DD requires both figures in the account disclosure (12 CFR 1030.4(b)) and the APY in any advertised rate (12 CFR 1030.8), which is why two accounts are easiest to compare by APY. This calculator divides the rate you enter by 12 and compounds it monthly, so a 4% entry behaves like a 4.07% APY. To model a true 4.00% APY, enter 3.93, the nominal rate that compounds to 4.00% over 12 months.
Timing changes the result a little. The calculator adds each deposit at the end of the month, after that month's interest, so a deposit earns nothing in the month you make it. Moving the same $200 to the first of the month gives every deposit one extra month of growth: on the 10-year row at 4%, the balance rises from $29,449.96 to $29,548.13, a gain of $98.17. Banks usually accrue interest daily and post it monthly, so a real statement lands near these figures rather than exactly on them.
Insurance limits matter once a balance grows. The FDIC covers deposits up to $250,000 per depositor, per insured bank, for each account ownership category (12 U.S.C. 1821(a)(1)(E)), and the NCUA covers credit union shares to the same $250,000 limit (12 U.S.C. 1787(k)). Every balance in the table above sits far below that line, but a large starting balance projected over 20 years can cross it. Spreading money across ownership categories or separate institutions, not across branches of one bank, is what extends coverage.
Interest is taxable in the year it is credited. Savings account interest counts as gross income (26 U.S.C. 61(a)(4)), and a bank that pays you $10 or more in a year must send a Form 1099-INT (26 U.S.C. 6049). The calculator reports pre-tax interest, so the $5,449.96 earned on the 10-year, 4% row is gross, and the amount you keep depends on your federal and state bracket. Interest under $10 is still taxable even though no form arrives.
Common mistakes
- Assuming the annual interest rate stays fixed for the entire time horizon, when real savings account rates move up and down with the broader rate environment.
- Entering the interest rate as a decimal such as 0.045 instead of a percentage such as 4.5, which produces a projection with almost no growth.
- Ignoring that this projection is pre-tax. Interest earned in a standard savings account is generally taxable income, which reduces the real amount you keep.
- Treating the monthly contribution as something that never changes, when most savers increase or pause contributions as income and expenses shift over time.
- Confusing compounding frequency with how often interest actually gets credited at your specific bank, which can differ from the monthly, quarterly, or annual options modeled here.
- Overlooking account fees, minimum balance requirements, or promotional introductory rates that step down to a lower standard rate after a set number of months.
Limitations
This calculator holds one annual rate, one monthly deposit, and one compounding schedule fixed for the whole horizon, and it treats the rate you enter as a nominal rate that it divides by the compounding frequency. Regulation DD defines the annual percentage yield as the return with compounding already included (Appendix A to 12 CFR Part 1030), so a quoted APY entered as the rate compounds a second time here and slightly overstates the balance, about 0.07 percentage points of yield at 4%. Savings and money market rates are variable, and a bank can change them at any time, so a multi-year projection drifts further from a real statement the longer it runs. The projection subtracts no monthly maintenance, minimum-balance, or excess-withdrawal fees, which the bank must list in the account disclosure under 12 CFR 1030.4(b)(4) but which this tool does not read. Interest is reported before tax even though it counts as gross income in the year it is credited (26 U.S.C. 61(a)(4)), and the model ignores inflation, deposits that change over time, promotional rates that expire, and the FDIC and NCUA $250,000 insurance limits (12 U.S.C. 1821(a)(1)(E) and 12 U.S.C. 1787(k)).
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